Method and apparatus for obtaining purified liquid oxygen



Aug. 20, 1946. Y A w. DENNIS -406,003

METHOD AND APPARATUS FOR OBTAINING PURIFID LIQUID OXYGEN Filed oct. 1, 1943 y ATTORNEYS v Patented Aug. 20, 1946 UNITED STATES PATENT oFFlcE METHGD AND APPARATUS FOR OBTAINING PURIFIED LIQUID OXYGEN v Wolcott Dennis,

Darien, Conn., assigner Reduction Company, Incorporated, New vN. Y., a corporation of New to Air York, York Application October 1, 1943, Serial No. 504,578

claims. (ci. fsa-115.5)

This invention relates to the separation and recovery of pure liquid oxygen from by liquefaction and rectification,

atmospheric air eliminated eectively.

In the usual methods of separating oxygen from suitable for many uses.

It is the object of' th vide a method and app yield of liquid oxygen free from as those mentioned.

.another object of L panying drawing, illustrating e present invention to proaratus which aii'ord a high impurities such able for the practice of the invention.

In carrying out the invention, the air is iniisan auxiliary column operatlng at low pressure,

for example .column 5 is provided a little above with an apparatus suitand vaporizer section caps 8, eecting partial rectication of the liquid air introduced through the pipe I6.

A condenser section ii having a plurality of tubes I8 is provided in the column 5, and the vaformed in the condenser tubes. l 9 is comparatively rich in nitrogen, since most of the oxygen has been separated on the trays i in the form of liquid which accumulates in the vaporizer section i3.

the separation-of the desired constituents. eiiiuent or waste gas escapes through a pipe 28 from the top of the column.

Surrounding the condenser tubes I9 is a vaporizer section 2 is liquid contains the impurities hereinbefore mentioned. To remove the impurities, the liquid is conveyed through a pipe 30 into the condenser section I1. oi' the column5 where it surrounds the tubes I8. 'I'he liquid in the vaporizer 29 is under relatively low pressure, but the liquid in the condenser section I1 is under a static head of the column of liquid in the pipe 30 29. 'I'he liquid is vaporized section I1, affording oxygen in in the condenser the vapor phase, free from impurities. The latter remain in phase oxygen the condenser section il'. The vapor is conveyed through a pipe 3l to a coil 32 submerged in the liquid surrounding the tubes I9, and since this vapor is under the static head provided as hereinbefore described, readily lqueed by heat exchange with the liquid in the vaporizer 29. The liquid oxygen product; is withdrawn from the coil 32 through a pipe 33 controlled by a valve 34 and is delivered to any suitable storage receptacle.

A purge 35 controlled by a valve 3B is connected to the condenser section l1 to permit withdrawal from time to time of liquid containing impurities. Purges 31 and 38, controlled by valves 39 and 4D, similarly permit removal of liquid from the vaporizer sections i3 and 29.

By locating the condenser section l1 in the high pressure column at a point below the main oxygen vaporizer 28, it is possible by virtue of the liquid head available, to vaporize the impure oxygen product at su'icient pressure to cause the evolved vapor to condense in the condenser coil 32 by heat exchange with the liquid surrounding the coil at lower pressure. Since all feeds to the low pressure column are substantially liquid and since the vaporizer is situated at the lower end of said column, it is possible to maintain a maximum of reflux thus ensuring a high degree of rectification. The method and apparatus as described afford a more eicient procedure and structure permitting the recovery o! oxygen in a liquid form free from impurities and substantially without serious losses.

Various changes may be made in the details of the apparatus and the operation thereof without departing from the linvention or sacrificing the advantages thereof.

I claim:

1. The method of recovering liquid oxygen free from impurities by separation from atmospheric air which comprises separating nitrogen from the oxygen of the air by liquefaction and rectification, thereby producing a. rst body of liquid oxygen, delivering liquid oxygen from the first body to a second body of liquid at a lower level under 4 the static head o! th'e first body. vaporizing the liquid oxygen of the second body by heat exchange with vapors produced by the rectification and reliquefying the oxygen vapor by heat exchange with the rst body ot liquid oxygen.

2. The method of recovering liquid oxygen tree from impurities by separation from atmospheric air which comprises separating nitrogen from the oxygen of the air by liquefaction and rectification, thereby producing a first body of liquid oxygen at a pressure slightly exceeding one atmosphere, delivering from the rst body to a second body lower level under the static head of the first body, vaporizing the liquid oxygen of the second body by heat exchange with vapors produced by the rectification and reliquefying the oxygen vapor by heat exchange with the rst body of liquid oxygen.

3. In the method of recovering liquid oxygen free from impurities by separation from atmospheric air, the steps of maintaining two bodies of liquid oxygen at different levels, the lower body being subject to the static head of the upper body, vaporizing oxygen from the lower body and reliquefying the vaporized oxygen by heat exchange with the liquid of the upper body.

4. In an apparatus for recovering liquid oxygen from atmospheric air, two superposed rectiers, a vaporizer at the bottom of the upper column, a vaporizer in the lower column, a connection between the two vaporizers whereby liquid in the lower vaporizer is subject to the static head of liquid in the upper vaporizer, andv a condenser in the upper vaporizer connected to the lower vaporizer to receive and reliquefy the vapor delivered from the lower vaporizer.

5. In an apparatus for recovering liquid oxygen from atmospheric air, means for maintaining two bodies of liquid oxygen at diierent levels, a connection whereby the body at the lower level is maintained under the static head of the liquid at the higher level, a condenser within the body at the higher level and means for delivering vapor from the body at the lower level to the condenser.

' WOLCOTT DENNIS. 

